#include <algorithm>
#include <iostream>
#include <map>
#include <numeric>
#include <string>
#include <utility>
#include <vector>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
#define FOR(i, begin, end) for (int i = (begin), i##_end_ = (end); i < i##_end_; i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)


#include <atcoder/string>
#include <atcoder/segtree>

int op1(int l, int r) { return min(l, r); }
int e1() { return 1 << 30; }


int main() {
    cin.tie(nullptr), ios::sync_with_stdio(false);
    int N, Q;
    string S;
    cin >> N >> Q >> S;

    auto sa = atcoder::suffix_array(S);
    auto lcp = atcoder::lcp_array(S, sa);
    lcp.push_back(0);

    vector<lint> rcs(N);
    vector<pint> st;
    st.emplace_back(N - 1, 0);
    IREP(i, N - 1) {
        while (st.back().second > lcp.at(i)) st.pop_back();
        rcs.at(i) = rcs.at(st.back().first) + lint(st.back().first - i) * lcp.at(i);
        st.emplace_back(i, lcp.at(i));
    }

    vector<int> sainv(N, -1);
    REP(i, N) sainv.at(sa.at(i)) = i;

    vector<lint> cs(N + 1);
    REP(i, N) cs.at(i + 1) = cs.at(i) + (N - sa.at(i));

    atcoder::segtree<int, op1, e1> lcptree(lcp);

    map<pint, lint> memo;

    while (Q--) {
        int l, r;
        cin >> l >> r;
        --l;
        if (memo.count(pint(l, r))) {
            cout << memo.at(pint(l, r)) << '\n';
            continue;
        }
        int len = r - l;
        int x = sainv.at(l);
        int b = lcptree.max_right(x, [&](int v) { return v >= len; });
        int a = lcptree.min_left(x, [&](int v) { return v >= len; });
        lint ret = cs.at(a) + lint(b - a + 1) * (len - 1);

        int h = len - 1;
        while (b < N and h) {
            int bnxt = lcptree.max_right(b, [&](int v) { return v >= h; });
            ret += lint(h) * (bnxt - b);
            b = bnxt;
            if (b < N) {
                ret += rcs.at(b);
                break;
            }
        }
        memo[pint(l, r)] = ret;
        cout << ret << '\n';
    }
}